Message Encryption FAQ

Have a question about how the new message protection capabilities work? Check for an answer here. Also, take a look at Frequently asked questions about data protection in Azure Information Protection for answers to questions about the data protection service, Azure Rights Management, in Azure Information Protection.

What is Microsoft Purview Message Encryption?

Microsoft Purview Message Encryption combines email encryption and rights management capabilities. Rights management capabilities are powered by Azure Information Protection.

Who can use Microsoft Purview Message Encryption?

You can use Microsoft Purview Message Encryption under the following conditions:

  • If you have never set up Office 365 Message Encryption (OME) or IRM for Exchange Online in Office 365.

  • If you have set up OME and IRM, you can use these steps if you are using the Azure Rights Management service from Azure Information Protection.

  • If you are using Exchange Online with Active Directory Rights Management service (AD RMS), you can't enable these new capabilities right away. Instead, you need to migrate AD RMS to Azure Information Protection first. When you've finished the migration, you can successfully set up Microsoft Purview Message Encryption.

    If you choose to continue to use on-premises AD RMS with Exchange Online instead of migrating to Azure Information Protection, you will not be able to use Microsoft Purview Message Encryption.

What subscriptions do I need to use Microsoft Purview Message Encryption?

To use Microsoft Purview Message Encryption, you need one of the following plans:

  • Microsoft Purview Message Encryption is offered as part of Office 365 Enterprise E3 and E5, Microsoft 365 Enterprise E3 and E5, Microsoft 365 Business Premium, Office 365 A1, A3, and A5, and Office 365 Government G3 and G5. You don't need additional licenses to receive the new protection capabilities powered by Azure Information Protection.

  • You can also add Azure Information Protection Plan 1 to the following plans to receive Microsoft Purview Message Encryption: Exchange Online Plan 1, Exchange Online Plan 2, Office 365 F3, Microsoft 365 Business Basic, Microsoft 365 Business Standard, or Office 365 Enterprise E1.

  • Each user benefiting from Microsoft Purview Message Encryption needs to be licensed to be covered by the feature.

  • For the full list see the Exchange Online service descriptions for Microsoft Purview Message Encryption.

Can I use Exchange Online with bring your own key (BYOK) in Azure Information Protection?

Yes! Microsoft recommends that you complete the steps to set up BYOK before you set up Microsoft Purview Message Encryption.

For more information about BYOK, see Planning and implementing your Azure Information Protection tenant key.

Do Microsoft Purview Message Encryption and BYOK with Azure Information Protection change Microsoft's approach to third-party data requests such as subpoenas?

No. Microsoft Purview Message Encryption and the option to provide and control your own encryption keys, called BYOK, from Azure Information Protection were not designed to respond to law enforcement subpoenas. OME, with BYOK for Azure Information Protection, was designed for compliance-focused organizations. Microsoft takes third-party requests for customer data seriously. As a cloud service provider, we always advocate for the privacy of your data. In the event we get a subpoena, we always attempt to redirect the third party directly to you to obtain the information. (Read Brad Smith's blog: Protecting customer data from government snooping). We periodically publish detailed information of the request we receive. For more information regarding third-party data requests, see Responding to government and law enforcement requests to access customer data on the Microsoft Trust Center. Also, see "Disclosure of Customer Data" in the Online Services Terms (OST).

Microsoft Purview Message Encryption is an evolution of the existing IRM and legacy OME solutions. The following table provides more details.

Comparison of legacy OME, IRM, and Microsoft Purview Message Encryption

Capability Previous versions of OME IRM Microsoft Purview Message Encryption
Sending an encrypted email Only through Exchange mail flow rules End-user initiated from Outlook for Windows, Outlook for Mac, or Outlook on the web; or through Exchange mail flow rules End-user initiated from Outlook for Windows, Outlook for Mac, or Outlook on the web; or through mail flow rules
Rights management - Do Not Forward option and custom templates Do Not Forward option, encrypt-only option, default and custom templates
Supported recipient type External recipients only Internal recipients only Internal and external recipients
Experience for recipient External recipients received an HTML message that they downloaded and opened in a browser or downloaded mobile app. Internal recipients only received encrypted email in Outlook for Windows, Outlook for Mac, and Outlook on the web. Internal and external recipients receive email in Outlook for Windows, Outlook for Mac, Outlook on the web, Outlook for Android, and Outlook for iOS, or through a web portal, regardless of whether or not they are in the same organization or in any organization. The encrypted message portal requires no separate download.
Bring Your Own Key support Not available Not available BYOK supported

How do I enable Microsoft Purview Message Encryption for my organization?

Will Office 365 Message Encryption (OME) be deprecated?

You can still use the previous version of message encryption called Office 365 Message Encryption (OME), it will not be deprecated at this time. However, we highly encourage organizations to use the new and improved message encryption solution. If you have not already deployed OME, you can't set up a new deployment of the previous version of OME.

My organization uses Active Directory Rights Management, can I use this functionality?

No. If you are using Exchange Online with Active Directory Rights Management service (AD RMS), you can't enable these new capabilities right away. Instead, you need to migrate AD RMS to Azure Information Protection first.

My organization has an Exchange Hybrid deployment. Can I use this feature?

On-premises users can send encrypted mail using Exchange Online mail flow rules. In order to do this, you need to route email through Exchange Online. For more information, see Part 2: Configure mail to flow from your email server to Microsoft 365.

What email client do I need to use in order to create an encrypted message? What applications are supported for sending protected messages?

You can create protected messages from Outlook 2016, Outlook 2013 for Windows and Mac, and from Outlook on the web. For more information on sending encrypted messages, see Send, view, and reply to encrypted messages in Outlook for PC.

What email clients are supported to read and reply to protected emails?

Microsoft 365 users can read and respond from Outlook for Windows and Mac (2013 and 2016), Outlook on the web, and Outlook mobile (Android and iOS). You can also use the iOS native mail client if your organization allows it. If you are not a Microsoft 365 user, you can read and reply to encrypted messages on the web through your web browser.

What email clients support the encrypt-only protected emails?

Microsoft 365 users can use Outlook for PC versions 2019 and Microsoft 365 to create mail protected with the encrypt-only policy. That means messages that have the new encrypt-only policy applied can be read directly in Outlook on the web, in Outlook for iOS and Android, and now Outlook for PC versions 2019 and Microsoft 365.

Is there a size limit for messages you can send with OME?

Yes. The maximum message size you can send with Microsoft Purview Message Encryption, including attachments, is 25 MB. For more information, see Message limits.

What type of messages does the encrypted message portal support?

The encrypted message portal only supports mail. The portal doesn't support other message types such as calendar or voice mail.

What file types are supported as attachments in protected emails? Do attachments inherit the protection policies and permissions associated with protected emails?

You can attach any file type to a protected mail. Protection policies are applied only to a subset of the file formats mentioned in File types supported by the Azure Information Protection client. Microsoft Purview Message Encryption only supports the following Office files extensions:

  • docx
  • docm
  • dotx
  • dotm
  • pptx
  • pptm
  • potx
  • potm
  • ppsx
  • ppsm
  • thmx
  • xlsx
  • xlsm
  • xlsb
  • xltx
  • xltm
  • xlam
  • xps

Microsoft Purview Message Encryption does not support the 97-2003 versions of the following Office programs: Word (.doc), Excel (.xls), and PowerPoint (.ppt).

Protection is inherited from mail to unencrypted attachments only. If a file format is supported, such as a Word, Excel, or PowerPoint file, the file is always protected, even after the attachment has been downloaded by the recipient. For example, say an attachment is protected by Do Not Forward. The original recipient downloads the file, creates a message to a new recipient, and attaches the file. When the new recipient receives the file, the recipient will not be able to open the protected file.

Are PDF file attachments supported?

The short answer is yes! If enabled in Exchange Online, PDF encryption allows you to protect sensitive PDF documents attached to emails. When you send an email, the Office 365 service encrypts PDF file attachments for Outlook on the web, Outlook for Mac, Outlook for iOS, and Outlook for Android. You can encrypt PDFs you send without any more steps.

Outlook Win32 does not natively support encryption of PDF file attachments. Instead, you'll need to set up Exchange mail flow rules or DLP policies to apply encryption to PDF attachments first. When you send mail from Outlook Desktop with a PDF attachment, the client sends the message with the attachment to the service first. When the service receives the file, the service applies the Microsoft Purview Message Encryption protection of the data loss prevention (DLP) policy or mail flow rule in Exchange Online. Next, Exchange Online sends the message with the protected PDF file attachment.

To enable encryption for PDF attachments, run the following command in Exchange Online PowerShell:

Set-IRMConfiguration -EnablePdfEncryption $true

PDF encryption allows you to protect sensitive PDF documents through secure communication or secure collaboration. For all Outlook clients, messages and unprotected PDF attachments inherit the Microsoft Purview Message Encryption protection of the data loss prevention (DLP) policy or mail flow rule in Exchange Online. Also, if an Outlook on the web user attaches an unprotected PDF document and applies protection to message, the message inherits the protection of the message. Users can only open the encrypted attachments in applications that support protected PDFs (for example, the encrypted message portal and the Azure Information Protection Viewer).

Important

Outlook Win32 client does not natively support PDF encryption even if PDF encryption is enabled.

Are SharePoint Online or OneDrive for Business attachments supported?

Not yet. SharePoint Online or OneDrive for Business attachments are not supported and end-users can encrypt a mail but not the cloud attachments.

What email clients support preview of encrypted attachments in protected emails?

When attachments are protected with a protected mail, Outlook clients provide tha ability to preview the document directly. Outlook supports preview of Office documents (docx, xlsx, pptx, doc, xls, ppt). Outlook on the web supports preview of Office documents (docx, xlsx, pptx) and PDF.

What email clients support revocation of protected emails?

Outlook on the web supports revocation of protected mail. See How to revoke an encrypted message that you sent for details.

Does the encrypted message portal support preview of encrypted attachments in protected emails?

The encrypted message portal supports preview of any encrypted attachment copies added to the encrypted mail. The support file types includes Word, Excel, PowerPoint, and PDF files.

Can I automatically encrypt messages by setting up policies?

Yes. Use mail flow rules in Exchange Online to automatically encrypt a message based on certain conditions. For example, you can create policies that are based on recipient ID, recipient domain, or on the content in the body or subject of the message. See Define mail flow rules to encrypt email messages in Office 365.

Can I automatically remove encryption on incoming and outgoing mail?

Admins can set up a mail flow rule to remove encryption for outgoing mail. You can only set up a rule to remove encryption for incoming mail that originates from your Exchange Online organization.

Can I automatically remove encryption on journal mail?

For an Exchange Online mailbox, admins must enable journal decryption and set up an Exchange Online journaling rule to generate a decrypted copy of the mail into the journaling mailbox. The journaling rule will take any mail or attachment that have encryption and send the original plus a decrypted copy into the journaling mailbox. You can only set up a journaling rule that can decrypt mail or attachments when the encrypted item originates from your organization.
To enable Exchange Online journaling:

Set-IRMConfiguration -JournalReportDecryptionEnabled $true

Can I automatically encrypt messages by setting up policies in Data Loss Prevention (DLP) through the Microsoft Purview compliance portal?

Yes! You can set up mail flow rules in Exchange Online or by using DLP in the Microsoft Purview compliance portal.

Can I customize encrypted messages with my company branding?

Yes, for mail sent from an Exchange Online mailbox in your organization! For information on customizing email messages and the encrypted message portal, see Add your organization's brand to your encrypted messages.

On what types of recipients do the encrypted message portal activity logs work?

The encrypted message portal activity logs only capture events for external recipients by accessing the encrypted message portals. Any activities in email clients triggered by external recipients are not recorded. For internal recipients, see Purview Audit (Premium) - Mail items accessed logs.

Are there any reporting capabilities or insights for encrypted emails?

There is an Encryption report in the Security and Compliance Center. See View email security reports in the Microsoft Purview compliance portal.

Can I use message encryption with compliance features such as eDiscovery?

Yes, most messages protected by Microsoft Purview Message Encryption are discoverable. Microsoft Purview Message Encryption protected mail that you receive from another Microsoft 365 organization that has custom branding applied through a mail flow rule is undiscoverable by your eDiscovery service. In other words, if the mail isn't accessible through the user's mailbox, but rather, surfaced only through a link to the encrypted message portal, the mail isn't searchable. See eDiscovery activities that support encrypted items for details.

Can I send as a shared mailbox and encrypt emails?

When someone sends an email message that matches an encryption mail flow rule, the message is encrypted before it's sent.

Can I open encrypted messages sent to a shared mailbox?

Yes! You can open encrypted messages for a shared mailbox. When the mail is sent from the same organization, you can open the mail when you're signed in to a supported Outlook client. If the mail is sent from an external organization, you'll need to use Outlook on the web.

  • Users can open protected mails in a shared mailbox where the shared mailbox received a protected mail as part of a distribution group.

  • Users can view attachments that inherit protection from email when they use Outlook for Windows, Outlook for Mac, Outlook for Android, Outlook for iOS, and Outlook on the web.

The following table lists the supported clients for shared mailboxes.

Platform Read mail View email attachments
Outlook on the web Yes Yes
Outlook for Windows Yes Yes
Outlook for Mac Yes Yes
Outlook for Android Yes Yes
Outlook for iOS Yes Yes

Note

Android and iOS would use the Office mobile app to view the encrypted attachments, and not directly in Outlook mobile.

There are currently two known limitations:

  • You can't open attachments to emails that you receive on mobile devices by using Outlook mobile.

  • In Outlook Win32, for users assigned to a shared mailbox through an email-enabled security group, the user will see a notification mail to view the encrypted mail using a web browser. In order to view the encrypted mail directly in Outlook Win32, Outlook and Azure Information Protection unified labeling clients require the user to be directly assigned to the shared mailbox with full access permissions and automapping enabled. Automapping is enabled by default for Exchange Online.

To assign a user to the shared mailbox

  1. Connect to Exchange Online PowerShell.aspx).

  2. Run the Add-MailboxPermission cmdlet with the Automapping parameter. This example gives Ayla full access permissions to a support mailbox.

    Add-MailboxPermission -Identity support@contoso.onmicrosoft.com -User ayla@contoso.com -AccessRights FullAccess -AutoMapping $true
    

Is delegated access supported with opening encrypted messages? Even if a delegate has full access to another user's mailbox?

Delegated access of encrypted mail is supported in Outlook on the web, Outlook for Mac, Outlook for iOS, and Outlook for Android. Outlook for Windows does not support delegated access.

How long do I have access to the mail in the encrypted message portal?

You can log in to the encrypted message portal to retrieve mail as long as the sender's organization is active and the mail has not been configured to expire.

What do I do if I don't receive the one-time pass code after I requested it?

First, check the junk or spam folder in your email client. DKIM and DMARC settings for your organization may cause these emails to end up filtered as spam.

Next, check quarantine in the Security & Compliance Center. Often, messages containing a one-time pass code, especially the first ones your organization receives, end up in quarantine.